Leased Lines

Leased lines are commonly referred to as dedicated connectivity options. This means that
the connection between the two endpoints is permanent in nature and that 100 percent of the
capacity is available to the end user. Leased lines are owned by the telecommunications carrier
and are often provided in the form of a T-1. These connections are also called point-to-point
links because the capacity of a leased line is dedicated to the corporation. Unfortunately,
because bandwidths cannot be shared, this type of connection is more expensive than Frame
Relay or ATM.
In addition, leased lines are also distance sensitive. Unlike Frame Relay, with leased lines, the
telephone company will charge the end user for both the local loop and the transit network. For
short distances, the differences in costs might be negligible, but for long distances, the costs
increase dramatically. For example, a 200-mile Frame Relay connection might cost $200 a
month, which would be the same as a 2,000-mile Frame Relay connection. The leased line
installation might also cost $200 a month for 200 miles, but most likely, it would cost $3,000
a month for the 2,000-mile link.
The most common leased-line service available in the United States is called a T-1. This provides
the corporation with 1.544Mbps of dedicated bandwidth. Older leased lines were digital
data service (DDS) circuits and yielded up to 56Kbps of bandwidth. These connections were
popular for mainframe connectivity at both the 9.6Kbps and 56Kbps levels.